I carried mail for 33 years. I learned years ago not to eat when it is cold outside. Your body's blood will go to your digestive system instead of the extremities (fingers/toes), and you'll only feel colder. I learned to eat lunch when I was done! If I started to feel cold, I'd move faster to get the blood moving, and to the extremities!
Same goes for riding. Blood will try to process the food you eat, rather than the muscles needed for cycling. Eat several hours or even better the day before a long ride, then eat after. Not during.
Oh, and they were putting road salt down at 6:30 this morning, in preparation for temps dropping through the freezing mark mid-day -- and snow accumulation tonight.
Nope, I'm definitely NOT riding tomorrow! But I'll still take some chili for the post-ride meal/chili competition afterwards!